Tarpaulins are commonly used to provide weatherproof cover over a particular area or mass of material. Many times, tarpaulins are used in conjunction with poles and ropes to create basic tent-like structures, providing protection from wind and rain. In the construction of such a structure, the tarpaulin must be stretched and secured across the poles to avoid the collapse of the structure and assure that the tent will not be overly affected by the wind. Tarpaulins may also be used to cover and protect materials during transportation in truck beds or to protect materials that are stored outside. In such instances, the tarpaulin is placed over the material and pulled taut by ropes connected to the corners of the tarpaulin. These ropes may be secured to a vehicle or storage structure. For example, an open end truck bed may be filled with material to be transported and subsequently covered by a tarpaulin secured by a rope or cable in order to protect it from the elements. The waterproof property of the tarpaulin will provide protection from rain and snow and, by pulling the tarpaulin taut, the large wind forces encountered during transportation will not be able to blow back the tarpaulin and expose the truck's load to the elements.
To assist in the securing of such covers, the corners of the cover material are folded over and stitched for reinforcement and are provided with an annular opening through which a grommet is fixed so that a rope or other securing means may be inserted therethrough and tied at a support. However, forces acting upon the grommet often cause the material to become raveled or stretched and, as a consequence, the grommet eventually breaks loose.
The prior art has addressed this problem by providing triangular and trapezoidal shaped comer reinforcement structures having upper and lower plates enclosed at two sides and open at the other sides thereof, thereby allowing for a tarpaulin or canvas cover to be inserted therethrough. These structures are also fixed with an annular opening for the placement of a grommet through which a rope or the like may be inserted. The corner reinforcement structures of the prior art are also constructed with rivet holes that provide a means for fastening the upper and lower plates to the corner of the material. Finally, the prior art has provided the upper and lower plates with a plurality of mating ribs and grooves that serve to interlock and pinch the corner material when the two plates are riveted together. Such prior art is generally exemplified by U.S. Pat. Nos. 4,777,071, 5,415,915 and 5,424,107.
The prior art, however, does not optimize the reinforcement of the corner inasmuch as the rivet holes, ribs and grooves of the reinforcement structures are not positioned in a manner that efficiently distributes the forces impacting the corner of the material. The prior art teaches a placement of the ribs and grooves to which the forces impacting the corner of the material are substantially parallel, creating a situation in which the ribs and grooves provide some, but far from optimal, reinforcement. Moreover, rivets secured through rivet holes as positioned in the prior art serve merely to clamp the corner reinforcement to the corner of the material and do little to optimize the reinforcement thereof.
There is a need in the art for a substantial improvement by utilizing both the placement of the rivet holes and the shape and placement of the ribs and grooves to optimize the reinforcement of the corner of the material.